In beef, poultry and turkey processing, the boning of animal carcasses generates bone by-products. The resulting bone by-products obtained from the boning process contain adhering fatty tissue and remnants of meat, and also a substantial content of high quality nitrogenous substances and lipids which originate from the bone content. Such materials are useful as high quality constituents for human and animal nutrition. Even if the meat is thoroughly removed manually from the bones, there still remains, for example on vertebra bones of cattle and pigs, up to 6% or more of meat, of which approximately 30% is connective tissue and about 15 to 25% is fat. Turkey and chicken bone by-products containing attached meat and skin can range from 60 to 72% of the chicken or turkey's green weight. As a rule, this part of the meat, together with the fat and the remaining protein and nitrogenous substances in bones, is lost as far as the manufacture of meat products useful for human and agricultural consumption. These by-products also pose a significant waste treatment and sanitary problem for the food processing industry.
Various animal carcass by-products resulting from a boning process have been treated in the prior art to produce cattle feed, fertilizer, meaty-flavored broth, and the like. These prior art procedures utilize urea, special enzymes, starch, fat solvents, acid treatments, and two-stage treatments among others. Other procedures involve treatment of bones to provide gelatin using soluble salts and special enzymes without extracting protein as an end product (see, U.S. Pat. No. 3,634,191).
These prior art procedures for the independent production of meat proteins, edible fat, broth and bone meal from the animal carcass by-products of processed beef, poultry and turkey are not completely satisfactory to realize the full commercial value of the starting materials. In view of the increasing shortage of animal protein, this loss of nutritionally valuable protein is a serious disadvantage. There continues to be a need for improved commercial processes to more efficiently recover the components of bone by-products or undervalued meat products, and to convert such materials into higher valued functional products.